Apparatus for rendering textile slivers uniform

ABSTRACT

Textile apparatus for reducing the unevenness in textile slivers. A card feeds sliver to a sensing device which detects any thickness variations and, through a draft control device, controls a variable speed motor which drives one of two pairs of drafting rollers, the other pair of which is driven at a substantially constant rate, the difference in speed between the pairs serving to draft the silver and also reduce the unevenness. An intermediate sliver storage device is located either (1) between the drafting rolls and the sliver coiler means which feeds the sliver into a can, or (2) between the card and the sliver sensing device. Photoelectric detecting means monitors the level of the sliver in the storage device and controls a second variable speed motor which, in the first modification drives the sliver coiler means, and in the second modification drives the card to maintain substantially constant the sliver level in the storage device. Either pair of drafting rolls may be variably driven, and each pair is provided with a tacho-generator to monitor its speed, the two tacho-generators operating in the event of any variation in the speed of the normally constant speed rolls to further vary, through the draft control device, the speed of the variable speed rolls to compensate for any erratic variation in the constant speed rolls. The second variable speed motor is controlled by varying the field current which effects a more gradual speed change and is advisable because of the high inertia of the card and the sliver coiler means.

United States Patent Krauss et al.

[45 1 Nov. 21, 1972 [54] APPARATUS FOR RENDERING TEXTILE SLIVERS UNIFORM [72] Inventors: Paul Krauss; Wolfgang Igel, both of Ebersbach, Germany [73] Assignee: Zinser-Textilmaschinen Gesellschaft mit beschrankter Haftung, Postfach, Germany [22] Filed: Sept. 30, 1970 I 211 Appl. No.: 76,707

[52] U.S. Cl. ..l9/240, 19/159 R [51] Int. Cl. ..D01h 5/38 [58] Field of Search ..l9/239, 240, 241, 106, 65 A,

[56] References Cited UNITED STATES PATENTS 3,184,798 5/1965 Burnet et al. ..19/65 R 3,099,048 7/ l 963 Locher 1 9/240 2,981,986 5/l96l Neil ..l9/240 Primary Examiner-Dorsey Newton Attorney-Edwin E. Greigg 5 7 ABSTRACT Textile apparatus for reducing the unevenness in textile slivers. A card feeds sliver to a sensing device which detects any thickness variations and, through a draft control device, controls a variable speed motor which drives one of two pairs of drafting rollers, the other pair of which is driven at a substantially constant rate, the difference in speed between the pairs serving to draft the silver and also reduce the unevenness. An intermediate sliver storage device is located either (1) between the drafting rolls and the sliver coiler means which feeds the sliver into a can, or (2) between the card and the sliver sensing device. Photoelectric detecting means monitors the level of the sliver in the storage device and controls a second variable speed motor which, in the first modification drives the sliver coiler means, and in the second modification drives the card to maintain substantially constant the sliver level in the storage device. Either pair of drafting rolls may be variably driven, and each pair is provided with a tacho-generator to monitor its speed, the two tachogenerators operating in the event of any variation in the speed of the normally constant speed rolls to further vary, through the draft control device, the speed of the variable speed rolls to compensate for any erratic variation in the constant speed rolls. The second variable speed motor is controlled by varying the field current which effects a more gradual speed change and is advisable because of the high inertia of the card and the sliver coiler means.

8 Claims, 5 Drawing Figures PATENTEDuuvzn nan SHEET 2 BF 2 fig. 4

APPARATUS FOR RENDERING TEXTILE SLIVERS UNIFORM The invention relates to an apparatus for producing uniform textile slivers and relates more particularly to an apparatus for producing uniform textile slivers with a driven source of sliver which serves to supply the sliver. The source of sliver is constituted by a preparatory spinning machine, with a driven sliver receiving device which serves to receive the sliver supplied and is more particularly constituted by adevice for depositing the sliver, with a draw (stretch) control mechanism which is located between the source of sliverand the sliver receiving device. The draw assembly comprises at least one pair of rollers which is driven at an essentially constant feeding speed and at least one further pair of rollers whose feeding speed is variable by a draft control device on the basis of the non-uniformity of the sliver as revealed by a sensing action performed by a sensing member, and further with an intermediate storage device for the sliver which is disposed between the source of the sliver and the sliver receivingdevice. The intermediate storage device being further equipped with means for sensing the extent to which this intermediate storage device is filled, with the sensing means being arranged to control the input or output speed of the sliver into or from the intermediate storage device for the sliver respectively in such a manner as to render constant the level to which the sliver is filled.

An apparatus of this type is known in which a main motor commonly drives a pluralityof carding machines or like preparatory spinning machines, which deliver or supply slivers, the combined fleeces being drawn off by a pair of rollers which is driven by the same main motor, the movable upper roller of the pair of rollers sensing the varying changes in thickness of these combined fleeces. The values obtained whichlindicate the irregularities of the sliver, are fed to a variable gear, which transmits the drive from the main motor with a speed which varies in such a manner as to reduce the ir regularities in thickness of the sliver which have been revealed to a pair of rollers, the latter being positioned downstream of the first-mentioned pair of rollers. The sliver, which has been rendered uniform in the stretch (drawing) control mechanism constituted by the two pairs of rollers then runs through an intermediate storage device for the sliver equipped with means for sensing the level to which this intermediate storage device is filled, to a drawing mechanism of a drawing frame, and thence to a sliver can. The drawing mechanism of the drawing frame is also driven by the main motor, although a variable gear is arranged in the drive transmission train and is variable according to the values obtained as a result of the sensing actions performed by the sensing means which serve to sense the level of the sliver in the intermediate storage device for the latter; in this way the speed at which the drawing (sensing) mechanism supplies the sliver is varied for the purpose of maintaining constant the level of sliver deposited in the intermediate storage device for the latter.

The invention improves on this known apparatus in the sense that it proposes that, if the feeding speed of p the pair of delivery (output) rollers, serving to draw the sliver from out of the drafting zone of the stretch (draw) control assembly, is acted on by the draft control device, then the intermediate storage device serving to store the sliver will be interposed between the draw (stretch) control assembly and the sliver receiving device, and the latter will be equipped with a variable speed device which is controlled by the draft control device, and this variable speed drive will follow the speed variations of the drive means of the delivery (output) pair of rollers of the drafting region of the drawing (stretch) control assembly in such a manner as to reduce these speed alterations or to subject these speed alterations to a time lag. Further, on the other hand, if the feeding speed of the pair of feed (input) rolls, serving to introduce the sliver into the drafting zone of the draw (stretch) controlmechanism, is acted on by the draft controldevice, then the intermediate storage device for the sliver will be interposed (as considered in the feeding direction of the sliver) between the sourceof sliver and the draw (stretch) control assembly and the source of sliver will be equipped with a variable speed drive which is controlled by the draft control device and follows the speed alterations of the drive of the pair of feed (draw-in) rolls of the drafting zoneof the draw (stretch) control assembly either with a reduction in these speed alterations or in such manner that a time lag is imposed on these speed alterations. When this expedient is adopted it is ensured that the assemblies of the source of sliverand that of the sliver receiving device these assemblies having very high mechanical inertia will not prevent the rapid changes in feeding speed, which are required for compensating short period fluctuations in the thickness of the sliver, of the stretch control assembly which is not acted on by the draft control device. Alternatively it will be thus ensured that these assemblies in their turn will not be subject to the high mechanical loads which such rapid speed alterations would mean for these assemblies (sliver source and sliver receiving device). Owing to the electrical coupling of the drive means of these assemblies to the drive of the pair of rollers which is susceptible of being acted on with regard to its feeding speed it is ensured that the supply of sliver and the receipt of sliver of these assemblies will on average follow in time the infeed and supply of sliver respectively of this pair of rollers. An embodiment of the invention which is particularly favorable in consequence of its high speed of reaction, is characterized in that the draft control device alters the current strength of the armature of these drives, constructed as electric motors, of the pair of rollers, acted on by the draft control device with regard to its feeding speed, of the stretch (draw) control assembly and of the slive receiving device or of the sliver source.

According to a further proposal of the present invention when there is used an intermediate storage device for the sliver together with means for sensing the level to which this intermediate storage device is filled, this sensing device being capable of acting on the delivery (draw-off) or feed (input) speed of the sliver from and into the intermediate sliver storage device respectively in such manner as to maintain constant the level of sliver in this intermediate storage device the sensing action whereby the level to which the intermediate storage device is ascertained is used for the purpose of superimposing a speed alteration on the speed alteration, affected by the draft control device, of the drive of the sliver receiving device or of the drive of the sliver source, this superimposed speed of alteration having the purpose of maintaining constant the level to which the intermediate sliver storage device is filled. If this expedient is adopted then it will be ensured that the level to which the intermediate storage device is filled can be maintained constant even when the electrical coupling of the variable speed machine parts does not suffice to maintain constant, for relatively long periods of time, the mean sliver feeding speeds of the coupled sliver conveying organs. A particularly satisfactory form of embodiment of an apparatus of this kind is characterized in that the speed of the drive, constituted as an electric motor, of the sliver source or of the sliver receiving device is variable by the means provided for controlling the level to which the intermediate sliver storage device is filled with a view to maintaining constant this level of sliver in the sliver intermediate storage device through acting on the field current strength of the electric motor. A control exercised in this way over the field current strength does in fact alter the motor speed more slowly than a control exercised over the current strength of the armature of the electric motor; however, as this speed alteration can in fact take place slowly, the advantage of the lesser costs entailed may be exploited. A further advantage of this proposal resides in the fact that there is no necessity for electrical superimposition of the draft control values obtained and of the values which are obtained as indications of the level to which the sliver is filled in the intermediate sliver storage device.

It is proposed in accordance with a further advantageous embodiment of the invention that the speed of the pair of rollers (of the stretch control mechanism), which is not affected by the drafting control device with respect to the feeding speed of this pair of rollers, should be measured, and when there is an alteration in the feeding speed of this pair of rollers, the speed of the other pair of rollers of this drawing mechanism should be altered by a corresponding amount. According to the invention this may take place, for example, by arranging for the speed of each of the pairs of rollers of the stretch control assembly to be measured by a respective tacho-generator and to be monitored in a draft control device for the purpose of ascertaining whether a selected strength or level of draft is being maintained. When deviations occur from the selected level or strength of drafting, the draft control device gives a signal for altering the feeding speed of the pair of rollers which are affected by it, this signal being such as to reduce the deviation from the selected or prescribed value. This mode of procedure has the advantage that, when an alteration in the speed of the pair of rollers whose speed should in principle be constant takes place for any reason whatsoever, this will not result in an incorrect strength or level of draft because this alteration in speed will be compensated by a corresponding speed alteration of the other pair of rollers which are associated with this drafting zone.

The present invention will now be more fully described by way of example, with reference to the accompanying drawings, wherein:

FIG. 1 is a side elevational view of an apparatus which constitutes a first embodiment of the invention,

FIG. 2 is a plan view of the apparatus illustrated in FIG. 1,

FIG. 3 is a side elevational view of an apparatus which constitutes a second embodiment of the invention,

FIG. 4 is a plan view of the apparatus illustrated in FIG. 3, and

FIG. 5 is a detail from FIGS. 1 and 2.

The drawing illustrates two embodiments of the invention, each of which comprises a carding engine provided with a sliver coiler. However, the invention is not restricted to this example of practical application, but can be applied to all preparatory spinning machines and combinations of such machines, which incorporate a sliver supply device and a sliver receiving device, for example, to sliver laps which comprise one or more carding engines and a drawing frame lying downstream of these carding engines or to sliver laps which comprise one or more first drawing frames, which deliver their slivers to a downstream-located second drawing frame or to a combing machine with a sliver coiler or the like.

In the two embodiments of the invention illustrated in FIGS. 1 and 2, or FIGS. 3 and 4, the source of sliver is constituted by a carding engine 1, of which only a few characteristic parts are diagrammatically illustrated, that is to say, the main drum 3, the doffer 5 with the doffer comb 7, the sliver funnel 9 and the drive which is in the form of an electric motor 10 or 10. In the embodiment illustrated in FIGS. 1 and 2, a pair of grooved rollers 12, 13 is provided in place of the normally employed pair of presser rollers of the carding engine. Between the rollers of said pair of grooved rollers 12, 13, the fleece which is separated by the doffer comb 7 from the doffer 5 and assembled in the sliver funnel 9 to a sliver 11 is further compacted (compressed), and at the same time is subjected to a sensing operation which is designed to check its thickness. For this purpose the lower grooved roller 12, for instance, is rotatably mounted from stationary bearings, whereas the upper comber roller 13 of this pair of grooved rollers is susceptible of being lifted against the biasing force of a biasing device, for example, spring means (not shown), owing to the presence of thicker portions in the sliver. The upward and downward movements of the comber roller 13 are sensed by a transducer 15 which derives measuring values corresponding to the magnitude of these upward and downward movements, and transmits these measuring values by way of a conductor 17 to a draft control device 19 which will be described below.

The grooved roller 12 which is mounted on shaft 21 is positively driven, through the intermediary of a train of gear wheels 23, by the drive of the carding engine 1. One of the shafts of a first pair of drafting rollers 27 is positively driven by the shaft 21, which acts through the intermediary of a further train of gear wheels 25. This pair of rolls 27 constitutes the pair of feed rolls of a drafting zone whose pair of delivery or output rolls is constituted by a second pair of drafting rolls 29, which are driven from a variable speed electric motor 31. The two pairs of drafting rolls 27, 29 may be of any known form of construction, for example, the lower driven rollers may be in the form of chilled steel rolls, whereas the upper rolls which are subject to the action of biasing devices and which roll in contact with the lower rollers may each comprise a resilient lining or cover. The driven shafts of each pair of rolls 27 29 each drive, through the intermediary of gear wheels 33 (or chains 34 in FIG. 4), tacho-generators 35 and 37. The signals which are generated by the tacho-generators 35 and 37 and which are indicative of the speed of the pairs of drafting rollers in each case, are fed to a draft control device 39 which will be described in greater detail below. i

Positioned downstream of the second pair of drafting rolls (output or delivery rolls 29) is an intermediate sliver storage device 40, serving to store the sliver and which may be of any suitable form of construction. In the present case this intermediate storage device is, for example, in the form of a so-called J-box. The intermediate sliver storage device 40 is provided with means for monitoring the level or charging condition of this intermediate sliver storage device 40; this monitoring device may, for example, be in the form of two spaced light barriers (photoelectric relays) 41, 42, which provide information as to the presence or absence of stored sliver in the cross-sectional area of the intermediate sliver storage device 40 to a charging level control device 44 for the sliver which will be described in greater detail below. During operation, the sliver is continuously fed into the intermediate sliver storage device 40 and is simultaneously and continuously discharged from the intermediate sliver storage device 40.

The sliver runs from the intermediate sliver storage device 40 into the sliver receiving device, by way of guide rolls 46; this sliver receiving device in this embodiment of the invention is being constructed as a sliver coiler 49 of known construction. The sliver is deposited into can 50 from the sliver coiler 49. The sliver coiler 49 is equipped with drive means including a variable speed electric motor 51'.

In the embodiment of the invention illustrated in FIGS. 3 and 4, all those parts which correspond to the parts of FIGS. 1 and 2, are given the same reference symbols. In the following description only those details and components contained in FIGS. 3 and 4 which differ from similar details and components contained in FIGS. 1 and 2 will be specially described.

The carding engine 1 is equipped with a variable speed drive means and the fleece which is combined to form a sliver of this carding engine 1 is, in the embodiment of the invention illustrated in FIGS. 3 and 4, compressed or compacted by a pair of presser rolls 53, which is conventionally used in carding engines. This pair of presser rolls 53 is used in this embodiment instead of the pair of grooved rolls 12, 13 which is employed in the embodiment illustrated in FIGS. 1 and 2. The pair of presser rolls 53 continuously supplies sliver to the intermediate sliver storage device 40, from which the pair of grooved rolls 12, 13 continuously removes this sliver. The intermediate sliver storage device 40 thus lies, in this embodiment, between carding engine 1 and the draw (stretch) control assembly which is constituted by the pair of grooved rolls 12, 13 and the pairs of drafting rolls 27 and 29. In the embodiment illustrated in FIGS..3 and 4, motor 31 drives one of the rolls of the rolls of the first pair of drafting rolls 27; the pair of grooved rolls 12, 13

is driven from the driven shaft of the roll of the first pair of drafting rolls 27, the drive being transmitted by way of the train of gear wheels 25. The second pair of drafting rolls is positively driven, by way of sprocket wheels and chain 56 from the sliver coiler 49; in this embodiment the sliver coiler 49 incorporates a drive 51 which operates at a constant speed.

In the embodiment illustrated in FIGS. 1 and 2, the feeding speed of the pair of delivery or output rolls 29 of the draw (stretch control assembly is variable by means of the drafting control device 19. For this purpose the downstream-located sliver receiving device 49 is also equipped with a corresponding variable speed drive 51', while the pair of feed or input rolls 27 and the carding machine 1 lying upstream of this pair of rolls are driven at a constant speed. In the embodiment illustrated in FIGS. 3 and 4, the feeding speed of the pair of feed or input rolls 27 of the drawing (stretch) control assembly is variable. Accordingly, the carding machine 1, located before or upstream of this pair of feed rolls 27, is equipped with a variable speed drive 10', whereas the pair of delivery or output rolls 29 of the drafting zone of the draw (stretch) control assembly also the sliver receiving device 49 which is arranged below or downstream of this pair of output rolls 29 are driven by means of a drive 51 at a practically constant drive speed.

The fluctuations in thickness of the sliver, which are sensed by the pair of grooved rolls 12, 13 of the devices illustrated in FIGS. 1, 2 or in FIGS. 3, 4, are converted in the transducer 15 into electrical pulses, which are indicative of these fluctuations in thickness of the sliver, and these measuring values are fed to the respective draft control device 19, where they are converted into control values which are known ti per se and will therefore not be described in detail here. These control values are fed, by way of conductor 55 to the drive motor 31 of thepair of variable speed rolls 27 (FIGS. 3,4) or 29 (FIGS. 1,2) of the respective draw (stretch) control assembly, and act on the degree of draft applied in this draw (stretch) control assembly in such a manner as to reduce the fluctuations in thickness of the sliver passing through this drawing or stretching assembly. This draft control device is, consequently, constituted by a control device which is capable of modifying the degree of draft applied to the sliver in a manner which varies according to the instantaneously sensed thickness of the sliver, and thus acts to compensate the sensed fluctuations in the thickness of the sliver.

In the case of the embodiments illustrated in FIGS. 1 and 2, the output of the draft control device 19 is also fed, by way of conductor 57, to the drive motor 51' of the sliver receiving device 49, so that the speed of this sliver receiving device 49 is also altered in the same sense as the speed of the pair of rolls 29. In the case of the embodiment of FIGS. 3 and 4, on the other hand, the control value of the draft control device 19 is fed, by way of conductor 58 to drive motor 10' of the card ing machine 1, so that the speed of the carding machine 1 will be varied in the same sense as that of the pair of rolls 27.

By reason of the low inertia of the pair of rollers (29 in FIGS. 1 and 2 M27 in FIGS. 3 and 4) whose feeding speed is variable, this pair of rollers rapidly follows the speed alterations which are imposed on it. Carding machine 1 and sliver receiving device 49, on the other hand, have a relatively high inertia and only follow the alterations in speed which are imposed onthem in a reduced or damped manner and/or subject to a delay (phase shift). This damping and/or phase shift can be amplified by a delay member 60 present in the conductor 57 (FIG.2) leading to the drive 51' or in the conductor 58 leading to the drive 10, conveniently, if the drive is in the form of an electric motor, this delay member may be in the form of a series resistance, possibly a variable resistance.

Owing to the speed differences between the pair of drafting rolls, whose feeding speed alters rapidly and which are controlled by the drafting control device and the carding machine 1 or sliver receiving device, whose feeding speed alters more slowly, reduction in the amount of the sliver and excess in the amount of sliver occur temporarily upstream of or downstream of the pair of rolls of the draw (stretch) control assembly whose feeding speed is variable; these fluctuations in the amount of sliver present being compensated for by the respective intermediate sliver storage device 40. Theoretically a mean length of a sliver loop, this mean length having once been established between the two sliver conveyor devices running at varying speeds, should maintain its mean length over a relatively long period of time in spite of the short period alterations in length of this sliver loop. However, as this is hardly possible in practice, it is found convenient to sense the level to which the sliver is charged in the intermediate sliver storage device 40 by means of the two light barriers (photoelectric relays) 41 and 42, the level of the sliver in the intermediate sliver storage device 40 being maintained constant, between the limits which are determined by the light barriers (photoelectric relays), in accordance with the principle of a two point control system which is known per se and is therefore not described in detail here. The speed of the drive of the carding machine 1 or of the sliver receiving device 49 is additionally altered in such a manner as to maintain constant the level of the sliver present in the intermediate sliver storage device 40, the signals, indicative of the condition of charging of the intermediate sliver storage device, supplied by the components 41, 42 being superimposed on the signals arriving from the device 19.

The alterations in speed of the drives referred to above can take place in any known manner, for example, by means of servo-motors which alter the speed of the drives. A particularly satisfactory form of construction is realized if the drives 10', 31 and 51' are in the form of electric motors, and if the drafting control device 19 changes the armature current of these electric motors according to particular requirements. It will also be found in many instances to be satisfactory if the device 44, serving to maintain constant the intermediate sliver storage device 40, modifies the field current of the motor 10' or 51 as and when required.

For the purpose of adjusting the level of drafting carried out in the draw (stretch) control assembly, only the feeding speed of one of the two pairs of rolls 29 or 27 is adjusted at any given time, and the feeding speed of the other pair of rolls should, desirably, remain constant. As this other pair of rolls is, however, positively driven from the carding engine 1 (FIGS. 1, 2) or from the sliver coiler (FIGS. 3, 4) and as the speed of these components can alter, for example, as a result of the lubricants used becoming heated and through the consequent reduction in the frictional resistance between the moving parts, the feeding speed of the pair of rolls which is not affected by the draft control device can vary within certain limits and result in the degree or level of draft imparted being varied in an unintended manner. When the degree or level of draft imparted is controlled in this manner, then this will lead to incorrect levels of draft being imparted. In order to avoid this the output signal corresponding to the speed of the pair of rolls which is unaffected by the draft control device 19 of the tacho-generator associated with this pair of rolls serves as guide value for the control exercised over the speed of the pair of rolls whose feeding speed is controlled as a function of fluctuations of thickness of sliver. A mean degree of draft can be set, at the draft control device 39, which is of a magnitude such that the thinnest section or portion of sliver whose deviation in thickness (from the established norm) still has to be compensated for by the control device 19, can in fact be compensated for by this control device 19; thus, the mean degree of draft which is to be applied to the sliver must be sufficiently high (for example, at least 1.25-fold) that, even when the thinnest sec tion or portion of sliver which still has to be controlled is introduced (for example, 25 percent reduction in cross section of the sliver), the level or degree of draft which has to be applied to the sliver will not fall below the value of l. The draft control device 39 performs a monitoring function to ensure that the level or degree of draft, set at any given time, will be maintained; the draft control device 39 performing this function by comparing the output signals delivered by the two tacho-generators 35 and 37 and delivering control pulses, by way of conductor 55, to the motor 31. These control pulses so alter the speed of this motor, and thus the circumferential speed of the pair of rolls 29 (FIG.2) or 27 (FIG.4), that the degree of draft which it is intended shall be applied to the sliver will be maintained in practice. As the signal of the tacho-generator 35 (FIG. 2) or 37 (FIG.4) serves as a guide value for this comparative measurement, the degree of draft intended will be in practice maintained even on the occasion of an unintended fluctuation in speed of the pair of rolls, which it is assumed, are of constant speed, or in consequence of fluctuations in the main electrical network, when this pair of rolls is gradually gathering speed in starting or when it is gradually losing speed when stopping or on the occasion of intentional slow running of the carding engine 1.

It is to be understood that this control exercised over the degree of draft which it is intended to impart to the sliver is superimposed on the control which is exercised on the draft, on the basis of irregularities in thickness of sliver sensed by the pair of rolls 12, 13, by the draft control device 19, so that the fluctuations in thickness of the sliver are reduced by the draw (stretch) control mechanism to an extent which is determined by the drafting control device 19.

That which is claimed is:

1. Apparatus for producing uniform textile slivers comprising:

a sliver feeding device (1);

a sliver receiving device (49);

9 separate electric motors (10 and 51 or 10' and 51) for driving said feedingand said receiving devices,

one motor being of constant speed and the other of variable speed; a sliver sensing device (12, 13) intermediate said feeding and receiving devices; a draft control device (19) controlled by said sensing device, an intermediate sliver storage device (40) intermediate said feeding and receiving devices, and means (41, 42) for detecting the level of sliver therein, said detecting means being operatively connected to a charging level control device (44) for controlling said variable speed motor whereby to maintain asubstantially constant level of sliver in said storage device; drafting device intermediate said feeding and receiving devices comprising a pair of driven feed rolls (27) and a pair of driven output rolls (29), one of said pairs of rolls being driven at a substantially constant speed;

a second variable speed motor (31) for driving the other of said pairs of rolls and controlled by said draft control device to eliminate sliver unevenness detected by said sensing device; and

said draft control device being operatively connected 7 to both variable speed motors whereby their speeds are concurrently controlled by'the sliver sensing device and the speed of said first variable speed motor may be varied independently of said sliver level detecting means (41, 42).

2. The apparatus of claim 1, wherein a time delay means (60) is provided between the draft control device and the first named variable speed motor so that there is a time lag between the respective speed changes of the two variable speed motors.

3. Apparatus for producing uniform textile slivers comprising:

a sliver feeding device (1 a sliver receiving device (49);

a constant speed electric motor (10) for driving said feeding device (1);

a first variable speed electric motor (51') for driving said receiving device (49);

a sliver storage device (40) intermediate said feeding and receiving devices, and means (41, 42) for detecting the level of sliver therein;

a drafting device (27, 29) intermediate said feeding and sliver storage devices having a pair of driven feed rolls (27) and a pair of driven output rolls (29), said feed rolls being driven at a substantially constant speed;

a second variable speed motor (31) for driving said output rolls;

a sliver sensing device (12, 13) intermediate said feeding device and said output rolls;

a draft control device (19) controlled by said sensing device, said second variable speed motor being controlled by said draft control device to eliminate sliver unevenness detected by said sensing device;

'10 said first variable speed motor being operatively connected to said draft control device whereby it is controlled concurrently with said second variable speed motor by said sensing device, said sliver level detecting means (41, 42) being operatively onnectedt a char in level ontrol device 44 for controliing said fl lSt variable speed m otoi whereby a substantially constant level of sliver is maintained in said storage device.

4. The apparatus of claim 3 comprising speed measuring means (35, 37) operatively connected with said drafting rolls (27, 29) for monitoring the relative speeds of the two pairs of rolls and for transmitting the readings to the draft control device to vary the speed of said output rolls responsive to any variation in the speed of said feed rolls.

5. The apparatus of claim 4 in which the speed measuring means includes a tacho-generator.

6. Apparatus for producing uniform textile slivers comprising;

a sliver feeding device (1),

a sliver receiving device (49);

a constant speed electric motor (51) for driving said receiving device (49); g

a first variable speed motor (10') for driving said feeding device (1);

a sliver storage device (40) intermediate said feeding and receiving devices, and means (41, 42) for detecting the level of sliver therein;

a drafting device (27, 29) intermediate said sliver storage and receiving devices, having a pair of driven feed rolls (27) and a pair of driven output rolls (29), said output rolls being driven at a sub-' stantially constant speed;

a second variable speed motor (31) for driving said feed rolls,

a sliver sensing device (12, 13) intermediate said feeding device and said output rolls;

a draft control device (19) controlled by said sensing device, said second variable speed motor being controlled by said draft control device to eliminate sliver unevenness detected by said sensing device;

said first variable speed motor being operatively connected to said draft control device (19) whereby it is controlled concurrently with said second variable speed motor by said sensing device, said sliver level detecting means (41, 42) being operatively connected to a charging level control device (44) for controlling said first variable speed motor whereby a substantially constant level of sliver is maintained in said storage device.

7. The apparatus of claim 6 comprising speed measuring means (35, 37) operatively associated with said drafting rolls (27 29) for monitoring the relative speeds of the two pairs of rolls and for transmitting the readings to the draft control device to vary the speed of said feed rolls responsive to any variation in the speed of said output rolls.

8. The apparatus of claim 7 wherein the speed mea suring means includes a tacho-generator. 

1. Apparatus for producing uniform textile slivers comprising: a sliver feeding device (1); a sliver receiving device (49); separate electric motors (10 and 51'' or 10'' and 51) for driving said feeding and said receiving devices, one motor being of constant speed and the other of variable speed; a sliver sensing device (12, 13) intermediate said feeding and receiving devices; a draft control device (19) controlled by said sensing device, an intermediate sliver storage device (40) intermediate said feeding and receiving devices, and means (41, 42) for detecting the level of sliver therein, said detecting means being operatively connected to a charging level control device (44) for controlling said variable speed motor whereby to maintain a substantially constant level of sliver in said storage device; a drafting device intermediate said feeding and receiving devices comprising a pair of driven feed rolls (27) and a pair of driven output rolls (29), one of said pairs of rolls being driven at a substantially constant speed; a second variable speed motor (31) for driving the other of said pairs of rolls and controlled by said draft control device to eliminate sliver unevenness detected by said sensing device; and said draft control device being operatively connected to both variable speed motors whereby their speeds are concurrently controlled by the sliver sensing device and the speed of said first variable speed motor may be varied independently of said sliver level detecting means (41, 42).
 1. Apparatus for producing uniform textile slivers comprising: a sliver feeding device (1); a sliver receiving device (49); separate electric motors (10 and 51'' or 10'' and 51) for driving said feeding and said receiving devices, one motor being of constant speed and the other of variable speed; a sliver sensing device (12, 13) intermediate said feeding and receiving devices; a draft control device (19) controlled by said sensing device, an intermediate sliver storage device (40) intermediate said feeding and receiving devices, and means (41, 42) for detecting the level of sliver therein, said detecting means being operatively connected to a charging level control device (44) for controlling said variable speed motor whereby to maintain a substantially constant level of sliver in said storage device; a drafting device intermediate said feeding and receiving devices comprising a pair of driven feed rolls (27) and a pair of driven output rolls (29), one of said pairs of rolls being driven at a substantially constant speed; a second variable speed motor (31) for driving the other of said pairs of rolls and controlled by said draft control device to eliminate sliver unevenness detected by said sensing device; and said draft control device being operatively connected to both variable speed motors whereby their speeds are concurrently controlled by the sliver sensing device and the speed of said first variable speed motor may be varied independently of said sliver level detecting means (41, 42).
 2. The apparatus of claim 1, wherein a time delay means (60) is provided between the draft control device and the first named variable speed motor so that there is a time lag between the respective speed changes of the two variable speed motors.
 3. Apparatus for producing uniform textile slivers comprising: a sliver feeding device (1); a sliver receiving device (49); a constant speed electric motor (10) for driving said feeding device (1); a first variable speed electric motor (51'') for driving said receiving device (49); a sliver storage device (40) intermediate said feeding and receiving devices, and means (41, 42) for detecting the level of sliver therein; a drafting device (27, 29) intermediate said feeding and sliver storage devices having a pair of driven feed rolls (27) and a pair of driven output rolls (29), said feed rolls being driven at a substantially constant speed; a second variable speed motor (31) for driving said output rolls; a sliver sensing device (12, 13) intermediate said feeding device and said output rolls; a draft control device (19) controlled by said sensing device, said second variable speed motor being controlled by said draft control device to eliminate sliver unevenness detected by said sensing device; said first variable speed motor being operatively connected to said draft control device whereby it is controlled concurrently with said second variable speed motor by said sensing device, said sliver level detecting means (41, 42) being operatively connected to a charging level control device (44) for controlling said first variable speed motor whereby a substantially constant level of sliver is maintained in said storage device.
 4. The apparatus of claim 3 comprising speed measuring means (35, 37) operatively connected with said drafting rolls (27, 29) for monitoring the relative speeds of the two pairs of rolls and for transmitting the readings to the draft control device to vary the speed of said output rolls responsive to any variation in the speed of said feed rolls.
 5. The apparatus of claim 4 in which the speed measuring means includes a tacho-generator.
 6. Apparatus for producing uniform textile slivers comprising: a sliver feeding device (1), a sliver receiving device (49); a constant speed electric motor (51) for driving said receiving device (49); a first variable speed motor (10'') for driving said feeding device (1); a sliver storage device (40) intermediate said feeding and receiving devices, and means (41, 42) for detecting the level of sliver therein; a drafting device (27, 29) intermediate said sliver storage and receiving devices, having a pair of driven feed rolls (27) and a pair of driven output rolls (29), said output rolls being driven at a substantially constant speed; a second variable speed motor (31) for driving said feed rolls, a sliver sensing device (12, 13) intermediate said feeding device and said output rolls; a draft control device (19) controlled by said sensing device, said second variable speed motor being controlled by said draft control device to eliminate sliver unevenness detected by said sensing device; said first variable speed motor being operatively connected to said draft control device (19) whereby it is controlled concurrently with said second variable speed motor by said sensing device, said sliver level detecting means (41, 42) being operatively connected to a charging level control device (44) for controlling said first variable speed motor whereby a substantially constant level of sliver is maintained in said storage device.
 7. The apparatus of claim 6 comprising speed measuring means (35, 37) operatively associated with said drafting rolls (27, 29) for monitoring the relative speeds of the two pairs of rolls and for transmitting the readings to the draft control device to vary the speed of said feed rolls responsive to any variation in the speed of said output rolls. 